add deadlock mutex package

write to deadlock stderr after closing gocui

more deadlock checking

vendor/github.com/sasha-s/go-deadlock/deadlock_map.go

@@ -0,0 +1,10 @@
+// +build go1.9
+
+package deadlock
+
+import "sync"
+
+// Map is sync.Map wrapper
+type Map struct {
+	sync.Map
+}